COMMON WORK FOR ALL CIVIL JOBS IN THERMAL POWER STATION IRRESPECTIVE OF AREA.

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CONCRETE.

- All concrete works should conform IS:456 or Equivalent standards lik BS ,DIN etc.

- Mix design of concrete shall be used everywhere except for lean concrete and PCC.

- For lean concrete and PCC nominal /Volume mix is permitted.

- Design Mix should be carried out as per IS: 10262.

-Minimum Grade of  M 25 concreting to be done for all foundations including piling  .

- For Structural and other area M 20 grade of concreting can be done.

- For Underground and outdoor work M 25 concreting is to be carried out.

- Grade of concreting for critical foundations was already mentioned earlier. On enquiry same can again be furnished.

-Unless otherwise specified, 20 mm and down aggregates shall be used for all structural concrete works 

- 40mm and down aggregates may also be used under special conditions for mass concreting in foundation.

-All underground concrete structures like trenches, substructures of pump houses, all water retaining / carrying structures , etc., shall have super-plasticizer cum water proofing cement additive conforming to IS:9103. In addition, limit on permeability as given in IS:2645 shall also be met with.

-Sound and crushed stone aggregate shall be used for all concreting.

- All aggregate should be tested for alkali reaction. High percentage alkaline silica shall not be used.

- Lime stone aggregate shall no be used in general for machine foundations.

- The temperature of fresh concrete shall be maintained at about 25 deg. C . If necessary ICE cubes are

   generally used during casting to maintain the temperature.

-Plasticizer / super plasticizer / retarder  / pumping additive may be used as required and permitted by codes . The slump generally be kept in this range.

TG TOP DECK                                                                                 150   TO   200 mm

BFP /ID/FD/PA FANS /MILLS ETC                                               100    TO   150 mm

BLOCK  FOUNDATIONS                                                                100    TO   150 mm

COLUMN                                                                                          100     TO   150 mm  

-Plywood with film face form work shall be used for the top decks of all machine foundations and also for columns of TG foundation. Form work is the job which consume  number of man days in civil work

for fixing in position then using prop to support them all around . We have not come across any mechanical method to do it in faster way. Adjustment of support firmly behind the form work takes time. Sometime it disturbs the foundation bolts location to an unacceptable limit . Therefore bolt checking , shear pocket checking to be done only after form works. 

- Generally Portland cement  ( having specific gravity 3.15) can be used for all purposes. However there are two other cements are available in the market . Those are Portland - Blast furnace Slag cements and 

Portland - Pozzolan cement . The specific gravity of these cements varies from 2.85 to 2.94. These cements are also used widely.

- The mixes of grades M5 M10, M15, M20 ,M25 M30 etc correspond approximately to the mix proportions (1:4:8), (1:3:6), (1:2:4), (1:1.5:3) and (1:1:2) respectively. For concrete mixing ratio in all grades concrete, the mix has to be designed after testing all the materials including water in labs. For higher grade of concretes the mix has to be designed , it is the water to cement ratio plays a major part therefore the same has to be monitored. Therefore to achieve the grade conducting design mix is very important . Ratio arrives during design mix is to be followed for concreting.

- Base Raft and Top Deck of any any machine foundations shall be cast in single pour.

- Ultrasonic pulse velocity test shall be carried out for the top decks of all machine foundations and TG substructure to ascertain the homogeneity and integrity of concrete. In addition to that additional cubes are to be taken at a predetermined interval.

PICTURES GIVEN ABOVE ARE THE CEMENT MOULD USED FOR TAKINGS CUBES  DURING CONCRETING.

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